Name that part for 200

[Waterloo]

If you are seeing rust color coolant and it is leaking, do you have heat in the cab through the front vents? Leakage is sometimes blockage, and that sounds like coolant, if it is, it sounds very old... When was the coolant system last flushed? I am thinking a possible heater core, not saying it is... Just going from my experience. Any water on the floor on the passenger side? The heater core is located in the dash, passenger side, you need to pull the AC box apart, there is a condenser in there and then your heater core. If the truck has sat, it is not uncommon to have those gunk up and fail. It is a $435 part last time I checked with International, I found one from Peterbilt for $200. This is a good time to familiarize yourself with your local FleetPride parts dealer...

When you get this truck home, it would be a good idea to drain the coolant system, and really inspect it. Drain out the coolant, all of it. Inspect the hoses for softness, pressurize the system to check for possible leaks and weak areas, bad clamps, cracked fittings, etc. Only you can do this right, a shop will just steal your money. Winter is coming and that is when everything fails under the hood.

Your coolant system, you cannot refill these systems like you would your car, this is an EPA truck, so you will need to pull a vacuum on the coolant system to refill. If you do not use a vacuum to refill, you risk an air pocket and possibly damaging the motor. Always fill with a vacuum.

Where to buy coolant, call FleetPride, they sell it by the case, usually around $9 a gallon for the red house brand, they call their house parts OTR. That is what I use. After two in frames, one learns quite a bit...

You will need at minimum a 90psi air compressor, and a coolant recharge kit... Here is what I use on my ProStar...

Here is the kit to refill coolant, you will need an air compressor to use this...
https://amzn.to/35VvU71
Also, you WILL NEED one of these hand pumps to pressurize your coolant system, this is how you check for leaks and other more serious problems. The coolant system is where everything starts and many issues are diagnosed.

Here is the pump, it is identical to the Snap-On unit sold on the trucks...
https://amzn.to/34Ha0Eo

Here is the adapter you will need to attach to your ProStar coolant bottle...
https://amzn.to/35LfFtg

If you are going to own this truck, you need to learn how to work on it. These few tools will pay for themselves in your first use. If you are going to depend on a paid mechanic to keep this truck on the road, you will be broke in another few weeks.

If it is a bad heater core, AND I AM NOT SAYING IT IS, but the symptoms sound familiar...

Call International and get the part number, call FleetPride, Peterbilt and a Freightliner dealer for pricing. There are many parts that are used in all brands of trucks, these heater cores are one of those items. And get to know your local FleetPride shop, have them open a cash account for you so you get a discount. They know me by name in two of their branches, and give me a good discount. The international Dealer knows me by voice, they have my last 8 on a sticky note on their monitor.

On a side note: It sounds like your truck has rot lot, from sitting. I hope you have some money in the bank, because from the sounds of things, you are going to be doing some wrenching and in need of parts. I am a victim too, of lot rot, and a few other things... There is a learning curve with these EPA trucks. My last seven trucks were just like your pick up truck, just change the oil, grease, tires and brakes... A few repairs here and there, a million miles was easy to hit with little to any out of pocket expense. Now, these new EPA trucks, totally different animal, they are cry babies and in need of continual attention, and money. These are built and designed to have a 500,000 mile lifespan. once you are past that 500,000 mies, break out the wallet... Especially on a used fleet truck that more than likely has been severely neglected.

Best to get Insite NOW, and start buying tools...

One thing I discovered, was that from sitting, my driveline, the drive shaft u-joints were shot. They took grease, but were all rusted up inside from sitting. If this is a fleet truck, they are rarely ever greased... I would get under the truck and drop one of the driveshafts and remove a u-joint to really inspect. Odds are, you will be doing some work under there in the near future if this truck has been sitting for any length of time. I would also get under there to see IF the zerk fittings will accept grease, these shops will rarely ever tell you if you have a bad one. get a good grease gun, I use the Dewalt battery powered one... If you do not have the power gun, I would put that on my list, meanwhile, a good pistol grip one will do the job. Get the pistol grip, much easier to spot those bad zerks if you can get your other hand free. I found quite a few shot zerks under my truck when I purchased mine.